Recently I came across an interesting question: is there, and if so how big, a difference in picture quality between the modern (canon) lenses (prime/zoom) and the past time FD series, using a typical/standard lens? Well, that deserved a test.
Premises of the test:
Same scene, rock solid tripod, time release, same time and place, same setup (f4, t 0.5s, iso100) and post processing (wb, contrasts, curves, etc.):
Canon ef 50mm/1.4 (305Eur, Netherlands, January 2013) and Tamron 17-50/2.8 (305Eur, Netherlands, January 2013) on a Eos 500 vs. Samsung nx10 with a FD 55/1.2 ssc (275Eur, European ebay, January 2013).

(my humble and personal) conclusions:
The zoom lacks the 3d of the primes, while the 50/1.4 seems very natural I personally prefer (still!) the fd55/1.2 for its texture and smoothness (3d feeling?). Sharpness in all three cases seems very similar indeed although the fd seems less ‘clinical’ and the edges feel a bit more natural and real life-like.
Still – matter of personal opinion.